Reciprocity Effects

While a number of the films below are no longer available new, I’ve included information about them here just in case you find some in your refrigerator.

Films are typically designed to respond to light as expected from about 1 second to 1/1000 second. When exposure times are extremely short or get too long, additional exposure beyond what is indicated by the meter is necessary. On long exposures this is because as light continuously hits the film the emulsion begins responding to that more slowly. The tables below all relate to >1 second exposures.

In addition, color films may produce or experience color shifts. Though such shifts are generally insignificant at exposures of less than 1 minute, if you go beyond that shutter speed into even longer exposures, try adding a CC10M or CC20M (color correcting) filter.

From Nikon Field Guide

Adjust exposure from the meter reading in the number of stops as follows:

*Assumes CC25 filter for shorter exposures, CC50 for 10-second+ exposures

None = No compensation required NR = Not recommended

Film manufacturers introduce new emulsions less frequently than before digital. Nevertheless, film families tend to have similar tendencies. For example, when Fujichrome Provia (RDP II) was introduced to replace Fujichrome 100 (RDP), it shared the original’s excellent reciprocity characteristics and remained one of the few films that did not require any adjustment with exposures up to 4 seconds. Thus, while some of the films listed are no longer produced, I’ve left the data for them here, as reciprocity characteristics tend to run in families.

Kodak Recommendations

For critical applications, Kodak doesn’t recommend exposures of 10 seconds or longer with most of their color slide films and suggests the following combination of exposure compensation and filtration for 1-second exposures:

NR = Not recommended

*Pro versions are +.5 stop with CC05B.

**Also recommended at 10 seconds +.5 stop with CC10R.

Most Kodak black-and-white films suggest 1 extra stop of exposure at 1 second, 2 stops at 10 seconds, and 3 stops at 100 seconds. Note that the C-41 processed T-Max T400CN has no reciprocity out to 120 seconds.

Ilford Recommendations

Ilford treats reciprocity failure slightly differently, giving a multiplication factor (P) for metered shutter speed on long exposures :